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Animal Behaviour
Journal Prestige (SJR): 1.58
Citation Impact (citeScore): 3
Number of Followers: 188  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0003-3472 - ISSN (Online) 1095-8282
Published by Elsevier Homepage  [3163 journals]
  • The importance of group vocal behaviour in roost finding
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Maria Sagot, Caroline R. Schöner, Abigail J. Jago, Imran Razik, Gloriana ChaverriIndividuals benefit from socially acquired information to avoid predation risks and enhance foraging efficiency. Spix's disc-winged bats, Thyroptera tricolor, form very stable social groups despite their need to find a new roosting site daily. Thyroptera tricolor produce two contact calls: inquiry calls, emitted during flight, and response calls, produced by bats after finding a suitable roost (in a furled leaf). Bats within social groups exhibit consistent individual differences in vocal behaviour and thus, groups are composed by a mix of less vocal and more vocal individuals. To date, it is not known whether consistent individual differences in contact calling behaviour decrease the time required for roost finding and whether vocal behaviour is correlated with an individual's ability to quickly locate roosts, thus constituting a behavioural syndrome. Here, we compared the time spent by social groups in finding roosts when a bat called from inside the roost, either frequently or infrequently. Moreover, we estimated how well calling rates inside a roost predicted a bat's ability to later find a new roost. Results of behavioural experiments and field observations show that social groups enter roosts faster when the bat inside the roost called more. This suggests that more frequent calling decreases search time, which may allow groupmates to save energy and decrease exposure to predators. Moreover, vocal activity also predicted discovery of more roosts (furled leaves) in their natural habitat, which emphasizes the relevance of more vocal individuals for the group. Our work represents a step in understanding the importance of communication and individual vocal behaviour in group formation and stability in gregarious animals.
       
  • Can starlings use a reliable cue of future food deprivation to adaptively
           modify foraging and fat reserves'
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Menno van Berkel, Melissa Bateson, Daniel Nettle, Jonathon DunnRegulation of mass in small birds is based on simultaneously minimizing starvation and predation risk, but the mechanisms birds use to assess starvation risk are still debated. While we know that birds anticipate periods of unpredictable food availability/energy expenditure (e.g. the winter and night) by increasing their fat reserves, we do not know whether this anticipation involves learning. This study investigated whether birds could learn to use a light cue that predicted a period of food unavailability, to adaptively regulate their foraging and/or body weight. Sixteen captive starlings, Sturnus vulgaris, were subjected to 42 days of an irregular schedule of food deprivation that involved depriving them of food for 5 h on 20 pseudorandomly chosen days. Birds were randomly allocated to two treatment groups for which a 30 min period of reduced ambient light either provided perfect information (Predictable) or no information (Unpredictable) about upcoming food deprivation. Both groups of birds increased their dawn body mass over the period of the experiment, consistent with a response to unpredictable food deprivation. However, no differences in either foraging behaviour or dawn body mass emerged between the groups, suggesting that the Predictable birds were unable to learn to use the light cue to initiate anticipatory foraging ahead of food deprivation. Furthermore, both groups immediately decreased their foraging behaviour in response to the onset of the light cue, suggesting that starlings do not have an evolved anticipatory foraging response to low light levels. Further work is needed to test alternative cues and designs before any general conclusions can be drawn regarding the flexibility of anticipatory foraging.
       
  • The contribution of shelter from rain to the success of pit-building
           predators in urban habitats
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Inon Scharf, Tomer Gilad, Michael A. Bar-Ziv, Noa Katz, Elena Gregorian, Jonathan N. Pruitt, Aziz SubachTrap-building predators are sit-and-wait predators that construct a trap and wait for other arthropods to be captured in their trap. The abiotic features of their microhabitat play a significant role in their foraging success, and trap relocation can be costly and risky. Wormlions are fly larvae that construct pits in loose soil to catch prey that fall into their pit-traps and serve as a fine example of a trap-building predator. Wormlions flourish in cities and often occur under buildings that provide shelter from direct sunlight and rain. Here, we studied in the laboratory and in the field the effect of simulated rain and soil moisture on wormlion (Vermileo sp.) habitat choice, response to prey and prey escape success. Wet soil had a strong negative effect on the wormlion pit size and its response to prey, and a positive effect on the probability of ant prey escaping the pit-trap. All these limitations led to a strong avoidance by wormlions of wet soil both before and after a pit was constructed, even at the cost of pit relocation. A field experiment comparing wet and dry plots nevertheless failed to show the expected directional relocation from wet to dry plots, and we provide several explanations as to why the patterns detected in the laboratory were less clear in the field. We suggest that rain presents a considerable limiting factor for wormlion hunting success, and that rain-shielding artificial structures could be responsible for the success of these predators in urban environments. It remains to be tested whether our results hold true for other trap-building predators and whether their preference for dry habitats is as strong as that of wormlions.
       
  • Urbanization alters the relationship between coloration and territorial
           aggression, but not hormones, in song sparrows
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Michelle L. Beck, Scott Davies, Kendra B. SewallMelanin-based coloration is associated with aspects of phenotype, including conspecific aggression and hormone concentrations. These relationships could arise as a result of genetic and/or biochemical links between melanin production and other traits. Additionally, anthropogenic change, including urbanization, exposes animals to novel conditions that can alter pigmentation, behaviour or hormones, potentially disrupting relationships between coloration and other traits. We examined relationships among the extent and darkness of melanin spotting on the breast of male song sparrows, Melospiza melodia, territorial behaviour, plasma testosterone and corticosterone concentrations to determine whether coloration was reliably associated with phenotype in this species. We conducted this study in urban and rural populations to determine whether relationships between coloration, behaviour and hormones varied between habitats. Males in urban habitat had more extensive brown spotting than rural males. The relationship between melanin coloration and territoriality differed in urban and rural habitats. In rural sparrows, territoriality was negatively correlated with spotting area, while in urban sparrows territoriality was positively associated with spotting darkness. Regardless of habitat, males with more extensive spotting increased testosterone secretion more in response to gonadotropin-releasing hormone administration and males with darker spotting had greater handling restraint-induced release of corticosterone. This suggests that plumage coloration is associated with underlying physiology, but the relationship between coloration and behaviour may shift between habitats.
       
  • Assortative interactions revealed by sorting of animal groups
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Alex Szorkovszky, Alexander Kotrschal, James E. Herbert-Read, Severine D. Buechel, Maksym Romenskyy, Emil Rosén, Wouter van der Bijl, Kristiaan Pelckmans, Niclas Kolm, David J.T. SumpterAnimals living in groups can show substantial variation in social traits and this affects their social organization. However, as the specific mechanisms driving this organization are difficult to identify in already organized groups typically found in the wild, the contribution of interindividual variation to group level behaviour remains enigmatic. Here, we present results of an experiment to create and compare groups that vary in social organization, and study how individual behaviour varies between these groups. We iteratively sorted individuals between groups of guppies, Poecilia reticulata, by ranking the groups according to their directional alignment and then mixing similar groups. Over the rounds of sorting the consistency of the group rankings increased, producing groups that varied significantly in key social behaviours such as collective activity and group cohesion. The repeatability of the underlying individual behaviour was then estimated by comparing the experimental data to simulations. At the level of basic locomotion, individuals in more coordinated groups displayed stronger interactions with the centre of the group, and weaker interactions with their nearest neighbours. We propose that this provides the basis for a passive phenotypic assortment mechanism that may explain the structures of social networks in the wild.
       
  • Corrigendum to “Caste-dependent brood retrieval by workers in the ant
           Formica exsecta” [Anim Behav 140 (2018) 151–159]
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Unni Pulliainen, Nick Bos, Patrizia d'Ettorre, Liselotte Sundström
       
  • Mind the trap: large-scale field experiment shows that trappability is not
           a proxy for personality
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Allison M. Brehm, Alessio MortellitiBehavioural tendencies vary consistently among individuals and this variation is known as personality. Previous studies have found that personality traits measured through standardized behavioural tests predict trappability (i.e. ‘trap happy’ versus ‘trap shy’). However, the nature of this relationship is unclear since it has been explored only within single species and never across environments. This is problematic because trappability is a labile characteristic that can vary between seasons, environments and years. It is essential to understand this link because there is great potential for the use of trappability as a proxy for personality. For example, if trappability reflects personality, this would allow researchers to extract personality data from long-term capture–mark–recapture data sets. To clarify this relationship, we designed a large-scale field experiment to measure personality and trappability in five small mammal species and across four distinct forest types. With an open field test, we quantified behaviour in 189 deer mice, Peromyscus maniculatus, 170 southern red-backed voles, Myodes gapperi, 42 American red squirrels, Tamiasciurus hudsonicus, 58 woodland jumping mice, Napaeozapus insignis, and 87 northern short-tailed shrews, Blarina brevicauda. We identified personality in all five of our target species, and through mixed-effects modelling we found that personality traits did not predict different aspects of trappability. Furthermore, trappability was not a repeatable measure (i.e. animals that were trap happy in one session were not necessarily trap happy throughout the trapping season). Our results suggest that trappability cannot be used as a proxy for personality.
       
  • State-dependent changes in risk-taking behaviour as a result of age and
           residual reproductive value
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Joe A. Moschilla, Joseph L. Tomkins, Leigh W. SimmonsAnimals are able to modify their behaviour in response to changes in their internal and environmental state. The asset protection principle predicts that an animal's risk-taking behaviour should vary as a result of its residual reproductive value (RRV); animals with greater RRV would incur a greater cost if injured or killed and should therefore take fewer risks than those with low RRV. Despite the intuitive appeal of this hypothesis, few studies have effectively separated the effects of RRV on behaviour from those of age. We addressed this weakness in the widely invoked hypothesis by measuring the risk-taking behaviour of female Australian field crickets, Teleogryllus oceanicus, at various points in the animal's lifetime. We found significant effects of age on risk-taking behaviour: older females emerged from a shelter sooner after a simulated predation threat and exhibited greater mobility in an open arena. Importantly, there was also a significant marginal effect of RRV on risk-taking behaviour. Females with lower RRV displayed greater levels of risk taking than females with high RRV. Our results thereby offer support for the asset protection principle as an explanation for state-dependent variation in risk-taking behaviour.
       
  • Individuals in larger groups are more successful on spatial discrimination
           tasks
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Ellis J.G. Langley, Jayden O. van Horik, Mark A. Whiteside, Joah R. MaddenTo understand how natural selection may act on cognitive processes, it is necessary to reliably determine interindividual variation in cognitive abilities. However, an individual's performance in a cognitive test may be influenced by the social environment. The social environment explains variation between species in cognitive performances, with species that live in larger groups purportedly demonstrating more advanced cognitive abilities. It also explains variation in cognitive performances within species, with larger groups more likely to solve novel problems than smaller groups. Surprisingly, an effect of group size on individual variation in cognitive performance has rarely been investigated and much of our knowledge stems from impaired performance of individuals reared in isolation. Using a within-subjects design we assayed individual learning performance of adult female pheasants, Phasianus colchicus, while housed in groups of three and five. Individuals experienced the group sizes in a different order, but were presented with two spatial discrimination tasks, each with a distinct cue set, in a fixed order. We found that across both tasks individuals housed in the large groups had higher levels of success than individuals housed in the small groups. Individuals had higher levels of success on their second than their first task, irrespective of group size. We suggest that the expression of individual learning performance is responsive to the current social environment but the mechanisms underpinning this relationship require further investigation. Our study demonstrates that it is important to account for an individual's social environment when attempting to characterize cognitive capacities. It also demonstrates the flexibility of an individual's cognitive performance depending on the social context.
       
  • Sociable bluegill, Lepomis macrochirus, are selectively captured
           via recreational angling
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Michael J. Louison, Jennifer D. Jeffrey, Cory D. Suski, Jeffrey A. SteinIndividuals often show considerable variance in social behaviour and aggression, leading to defined social roles. Removal of individuals with particular roles from groups may have impacts on group function, leaving those groups less able to locate critical resources and avoid danger. In recreational fisheries, capture by humans constitutes a mortality risk, and therefore angling has the potential to fundamentally alter social structure in exploited populations if individuals with defined social roles are disproportionately captured. However, little work has examined the linkage between social behaviour and angling vulnerability. To address this gap, we conducted a study on bluegill, Lepomis macrochirus, a freshwater fish known to be socially gregarious, and a common target of recreational anglers in North America. Fish were angled in a naturalistic pond setting, and a subset of captured and uncaptured fish was then assessed for sociability in a shoaling assay and aggression/dominance in paired dyadic contests. Results showed a significant effect of time spent in the social zone on capture status, with captured individuals spending significantly more time near a transparent divider separating it from a shoal of conspecifics compared to uncaptured fish. Dominance was not associated with angling vulnerability, and sociability was not linked with dominance. Collectively, these results show that more social bluegill are more likely to be captured by anglers. This could in turn lead to decreased social functionality in exploited populations as a result of the removal of particularly social individuals, as well as possible evolution of social behaviour in exploited populations due to this selection.
       
  • Working hypotheses on the meaning of general alarm calls
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Guillaume Dezecache, Mélissa BerthetGeneral calls are present in the vocal repertoire of a great number of animal species. Because of their lack of context specificity, they are typically argued to possess blurred meaning, or even no meaning at all. Although recent animal cognition studies have demonstrated a growing interest in these vocalizations, there is currently no clear definition of general calls, and their meaning is seldom discussed. Here, we propose a definition of general calls, and review various hypotheses regarding their meaning, focusing on alert contexts. We first discuss the hypothesis that general alarm calls have a general alert meaning. Second, we review an alternative view, that general calls in fact have a specific meaning. With this review, we encourage further research that could help delve into the mechanisms underlying vocal production and comprehension and would improve our understanding of general and specific calls in animals.
       
  • The fitness cost to females of exposure to males does not depend on water
           availability in seed beetles
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Maider Iglesias-Carrasco, Gizem Bilgin, Michael D. Jennions, Megan L. HeadAccess to multiple males can benefit a female in terms of increased fecundity and/or offspring performance. However, the presence of more males can also impose costs on females that arise from an elevated mating rate (e.g. due to increased genital damage, loss of feeding opportunities) and/or increased harassment. Different environments might influence the relative magnitude of these costs and benefits, because they can influence how often males and females encounter each other as well as the nature of these encounters. In the seed beetle, Callosobruchus maculatus, water is a limiting resource for females that can be obtained from male ejaculates. Here we explored whether the net fitness of female seed beetles is affected by breeding in either a dry or a wet environment when housed with differing numbers of males (none, one or four). Consistent with costly male harassment, females housed with four males laid significantly fewer eggs than those housed alone or with a single male, but there was no effect of the number of males on female egg-laying rate, life span, larval development rate or egg–adult survival of offspring. Although females in the wet environment lived significantly longer, there was only tentative evidence that water availability affected the net fitness cost to females of being exposed to more males. We conclude that to understand the evolution of mating systems it is important to explore how the environment affects female fitness by balancing the costs and benefits of being exposed to males.
       
  • To compete or not to compete: bushcricket song plasticity reveals male
           body condition and rival distance
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Marianna Anichini, Karl-Heinz Frommolt, Gerlind U.C. LehmannMales of several animals, including insects, use acoustic signals to attract a sexually receptive conspecific partner. In the orthopteran chorusing genus Poecilimon (Tettigoniidae), male signalling as well as female preference can be related to male body condition and to the social environment. Song is thought to be an honest signal of male quality, and song characteristics are therefore often important for sexual and social selection. At the same time, signal expression is plastic and this plasticity depends on the quality of the individual signaller, the acoustic components preferred by females and rivals' body condition and proximity. Using the bushcricket species Poecilimon ampliatus as a model, we investigated how both internal (body condition) and external (level of competition) factors affected the expression of temporal song characteristics. We show that both factors significantly affected acoustic signalling activity: when competing against light rivals, heavy males adjusted the characteristics of their songs to different social conditions. However, light males competing against a heavy rival showed less plasticity in their acoustic signals across social conditions. During the most escalated competition, heavier males increased their acoustic signal investment up to the maximum level, signalling with longer verses and higher duty cycles, in comparison to all other treatments. Body condition and the social environment affected male acoustic signal activity, which suggests that these factors mediate the allocation of resources for signalling and different strategies adopted in competition. The adaptive plasticity of acoustic signals in this species raises new questions about the potential role that this process could play in natural choruses, where more than two competitors are signalling simultaneously.
       
  • Behavioural thermoregulation alters microhabitat utilization and
           demographic rates in ectothermic invertebrates
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Gang Ma, Chun-Ming Bai, Xue-Jing Wang, Muhammad Z. Majeed, Chun-Sen MaThermoregulatory behaviours are of great importance for ectotherms buffering against the impact of temperature extremes. Such behaviours bring not only benefits but also organism level costs such as decreased food availability and foraging efficiency and thus lead to energetic costs and metabolic consequences. However, there remains an important gap in our knowledge to link thermoregulatory behaviour to population level ecological consequences. Aphids, as ectothermic invertebrates, can escape from thermal extremes by either dropping off the plant they are on or moving to suitable microclimates. Here we used the English grain aphid, Sitobion avenae, as a model system to test the hypothesis that aphids may behaviourally avoid heat stress while also altering their microhabitat utilization leading to demographic consequences. We found that heat stress drove the aphids to leave their host plant; this reduction in host plant residence was associated with increasing leaf temperatures indicating that aphids exhibit thermoregulatory behaviour to escape heat stress. Specifically, we found that behavioural thermoregulation made the aphids disperse and redistribute themselves within different microclimates and thus led to changes in microhabitat utilization. We also discovered that leaving the host plant during behavioural thermoregulation resulted in a considerable decrease in aphids' survival probability due to their inefficient relocation to other plants and increased risk of starvation. Finally, we found that the aphids' thermoregulatory behaviour prevented heat stress while concurrently resulting in decreased survival and reproduction. Together, these findings support our hypothesis that behavioural thermoregulation alters microhabitat utilization and demographic rates in aphids. This study highlights the importance of behavioural thermoregulation and its ecological consequences and has important implications for understanding population responses in the context of current climate change.
       
  • The influence of locomotory style on three-dimensional spatial learning
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Victoria A. Davis, Robert I. Holbrook, Theresa Burt de PereraThe degree of three-dimensional movement exhibited by animals depends, in part, on their style of locomotion. For example, surface-bound animals such as humans are always in contact with the ground and, consequently, their travel in the vertical dimension is largely dictated by the topography of the terrain. In contrast, nonsurface-bound (flying and swimming) animals can move equally in all three dimensions. Research from the last 20 years has indicated that many animals learn and remember information about the vertical and horizontal dimensions with different degrees of accuracy, and that this may be influenced by their style of locomotion; however, there has been no overview to determine whether these differences follow general patterns and there have been few attempts to explain the reasons behind them. The aims of this article are twofold. First, we review the literature on vertical and horizontal navigation, comparing the relative accuracy of these processes in surface-bound and nonsurface-bound animals, and critically appraising the key contributing factors. Second, we hope to establish a framework to help direct researchers interested in the effects of locomotory style on navigation to areas of the field where data are lacking or where there have been contradictory findings that need to be resolved. We suggest that as there are currently few studies investigating three-dimensional navigation, the field would benefit from more studies in a larger variety of species, in particular flying and swimming species that nest and forage on the ground or in the benthic zone and arboreal surface-bound animals that must regularly move in three dimensions through the canopy. This will enable us to determine whether real differences in spatial learning exist between animals exhibiting different styles of locomotion and, if differences do exist, allow us to establish general principles that can explain these differences in spatial learning between species.
       
  • Anthropogenic calling sites boost the sound amplitude of advertisement
           calls produced by a tropical cricket
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Bettina Erregger, Arne K.D. SchmidtAcoustic signals are widely used as sexual displays to attract mates. The choice of display site can strongly influence the male call characteristics and their attractiveness to females. Males can improve the conspicuousness of their signals by increasing sound amplitude and expanding their broadcast area thereby reaching more potential mating partners and influencing female choice. Insects possess a rather limited degree of signal plasticity. To increase the intensity of their calls, insects have been known to manipulate and engineer their display locations. Mole crickets, for example, build burrows that are shaped like horns, designing the burrow such that its resonance closely matches that of their call frequency, thereby boosting sound amplitude. Tree crickets manipulate plant leaves, using them as baffles for optimal sound radiation. In this study, we show for the first time that an insect species can enhance its advertisement calls by using novel, anthropogenic environments as singing sites. During this study, the tropical cricket Anurogryllus muticus was frequently found singing beside the walls of houses, on concrete stairs or in storm drains. These locations significantly increased the sound amplitude of its calls, by an average of 13 and 7 dB SPL, respectively, as measured above and in front of the singing animals compared to the sound amplitude measured in their natural grassland habitat. To evaluate the effect of calling site choice on the male's life span, we conducted a 35-day population survey using the mark and recapture method. Our results revealed that those males that called in grassland habitat without occupying burrows had the shortest minimum life spans.
       
  • Quantity discrimination in angelfish, Pterophyllum scalare: a novel
           approach with food as the discriminant
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Luis M. Gómez-Laplaza, Eva Díaz-Sotelo, Robert GerlaiThe ability to distinguish between different quantities of items is fundamental in many ecological contexts, and it has been shown in different animal species. This ability may also be context specific. Quantity estimation in fish has mainly been analysed in the context of social behaviour, whereas a majority of studies conducted with species other than fish tested it in the context of foraging. Surprisingly, little is known about the capacity of fish to discriminate between food quantities, possibly because of difficulties in testing individual fish in a novel, and thus aversive, test environment. Here, we present a novel approach that allowed us to test single angelfish, Pterophyllum scalare, while minimizing isolation-related stress. In binary choice tests, sets composed of similarly sized discrete food items differing in numerical size were presented and the spontaneous (untrained) choice of angelfish was investigated. In all contrasts tested in three experiments, angelfish preferred the numerically larger to the smaller food set. The performance of the fish was ratio dependent in the small but not in the large number range (more than four food items, contrasts that were investigated for the first time in fishes), and there was no significant difference in the magnitude of preference for the small versus the large values. However, overall results indicated that the response was ratio dependent, with an increase in accuracy as the numerical ratio between the contrasts increased. Furthermore, the same numerical ratios that were successfully discriminated with small quantities were also similarly discriminated with large quantities. Altogether, our results thus imply that angelfish utilize the approximate number system of quantity representation for the entire numerical range tested, and that their response is an attempt to maximize foraging success.
       
  • Subspecies status and methods explain strength of response to local versus
           foreign song by oscine birds in meta-analysis
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Timothy H. Parker, Emma I. Greig, Shinichi Nakagawa, Marcelina Parra, Anthony C. DalisioTo understand the implications of geographical variation in vocal culture in songbirds, researchers have often compared territorial responses to playback of local songs versus responses to playback of songs from ‘foreign’ conspecifics. This body of work has the potential to help us move towards a general understanding of factors driving divergence in signal recognition. We conducted a systematic review and meta-analysis of 57 playback studies to explain variation in strength of response to local versus foreign songs. Studies with incomplete reporting of results had elevated effects due to selective reporting. Studies that used small numbers of stimuli as exemplars (pseudoreplication) had more variable effects than studies without severe pseudoreplication. Whether or not we controlled for pseudoreplication, we found greater response to playback of local song than to foreign song. In investigating potential biological drivers of the variation in strength of experimental effects, we found that the difference in territorial response to local versus foreign song was stronger if the foreign song was recorded from another subspecies than if the foreign song was recorded from the same subspecies as the focal individuals. Indexes of risk of accidental response to heterospecific song did not coherently explain response to foreign conspecific songs, nor did factors expected to influence individual experience with foreign conspecific songs. Thus, although oscine songbirds clearly react more aggressively to local song than to foreign song and variation in the strength of this effect is influenced by methodological choices and subspecies status, considerable variation in the strength of response to local versus foreign song playback remains to be explained.
       
  • Experienced individuals influence the thermoregulatory fanning behaviour
           in honey bee colonies
    • Abstract: Publication date: August 2018Source: Animal Behaviour, Volume 142Author(s): Rachael E. Kaspar, Chelsea N. Cook, Michael D. BreedThe survival of an animal society depends on how individual interactions influence group coordination. Interactions within a group determine coordinated responses to environmental changes. Individuals that are especially influential affect the behavioural responses of other group members. This is exemplified by honey bee worker responses to increasing ambient temperatures by fanning their wings to circulate air through the hive. Groups of workers are more likely to fan than isolated workers, suggesting a coordinated group response. But are some individuals more influential than others in this response' This study tests the hypothesis that an individual influences other group members to perform thermoregulatory fanning behaviour in the western honey bee, Apis mellifera L. We show that groups of young nurse bees placed with fanners are more likely to initiate fanning compared to groups of nurses without fanners. Furthermore, we find that groups with young nurse bees have lower response thresholds than groups of just fanners. Our results suggest that individuals have the capability to influence other individuals to follow their fanning response as temperatures increase, and these social dynamics balance probability of fanning with thermal response thresholds. An influential individual may ultimately affect the ability for a society to efficiently respond to environmental fluctuations.
       
  • Collective exodigestion favours blow fly colonization and development on
           fresh carcasses
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Quentin Scanvion, Valéry Hédouin, Damien CharabidzéNecrophagous flies breeding on carcasses face high selection pressures and therefore provide interesting opportunities to study social adaptations. We postulated that gregariousness in necrophagous blow fly larvae is an adaptive response to the environmental constraints of fresh carcasses. Cooperation is indeed believed to be key to the global success of social species. To test this idea, the development of Lucilia sericata (Diptera: Calliphoridae) larvae growing on low- or high-digestibility food substrate (control or trypsin-added ground beef muscle, respectively) at different larval densities was monitored. Results showed that larvae developed faster and had decreased mortality at high than low larval density. Furthermore, aggregation had no deleterious effect on the morphological characteristics (e.g. size) of postfeeding larvae and adult flies. We concluded that increased density positively affected population fitness, which is a conclusion consistent with the predictions of the Allee effect. Compared with those fed on regular food, larvae fed on high-digestibility food had reduced mortality and faster development on average. From these results, we postulated that collective exodigestion might be an adaptive response allowing blow flies to colonize fresh carcasses before the arrival of other insects and the multiplication of microbes. This hypothesis is consistent with the idea that cooperation may enable species to expand their niches.
       
  • Brilliant-thighed poison frogs do not use acoustic identity information to
           treat territorial neighbours as dear enemies
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): James P. Tumulty, Andrius Pašukonis, Max Ringler, James D. Forester, Walter Hödl, Mark A. BeeSome territorial animals recognize familiar neighbours and are less aggressive to established neighbours than they are to strangers. This form of social recognition produces a ‘dear enemy’ effect, which may allow animals to reduce the costs of territory defence. The dear enemy effect is thought to reflect either the decreased threat posed by neighbours relative to strangers (the relative threat hypothesis) or the decreased need for escalation with increasing familiarity between neighbours (the familiarity hypothesis). We tested for a vocally mediated dear enemy effect in male brilliant-thighed poison frogs, Allobates femoralis. In this species, the familiarity hypothesis predicts a dear enemy effect, because males defend long-term stable territories and should be familiar with the calls of their neighbours. In contrast, the relative threat hypothesis does not predict a dear enemy effect, because neighbours and strangers both represent competitors for mates and likely pose equivalent threats. Acoustic analyses showed that males produce individually distinctive advertisement calls. Two playback experiments were conducted to determine whether territorial males respond less aggressively to neighbours' calls than to strangers' calls based on this acoustic identity information. In the first experiment, males pursued acoustically simulated neighbours and strangers to similar distances when calls were played both from the direction of the neighbour's territory and from a direction with no neighbours. In the second experiment, males responded aggressively to neighbours' and strangers' calls at similar threshold amplitudes and pursued these calls to similar distances. Hence, two different playback experiments failed to find evidence of a vocally mediated dear enemy effect. Our results support the hypothesis that territorial animals respond to the relative threat posed by neighbours and strangers regardless of their level of familiarity with neighbours.
       
  • Offspring are predisposed to beg more towards females in the burying
           beetle Nicrophorus vespilloides
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Matthieu Paquet, Hannah Drummond, Per T. SmisethIn species with biparental care, begging offspring may preferentially associate with or beg more towards one of their parents. Such preferences may reflect that the benefits of begging vary with the parent's sex given that females and males often differ in the amount of care they provide and/or in their responsiveness to begging levels. Alternatively, they may reflect the outcome of sexual conflict over care as females may deposit compounds into eggs tha talter offspring begging behaviour such that it increases male contributions towards care. For example, females might use male presence during egg laying as a cue for whether they might receive male assistance in care. Here, we studied offspring begging behaviour towards male and female parents in the burying beetle Nicrophorus vespilloides by manipulating male presence or absence during egg laying and providing larvae with a simultaneous choice between an unfamiliar female and male adult beetle. We then recorded begging behaviour of (1) naïve newly hatched larvae that had no prior experience of a parent and (2) larvae after 24 h of care by foster parents. Larvae showed a clear preference for associating with and begging towards females both when naïve and after 24 h of care. We found no evidence for prenatal maternal effects on larval begging behaviour. Our study reveals that offspring are predisposed to preferentially beg towards females independently of prior experiences with parents and highlights the importance of considering responses of begging offspring to parental attributes, such as the parent's sex, for our understanding of family conflicts.
       
  • Does the length of the night affect the timing of nocturnal departures in
           a migratory songbird'
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Florian Müller, Georg Rüppel, Heiko SchmaljohannMany animals perform their migratory movements within discrete time periods of the day/night cycle. Among migratory songbirds the majority of species generally restrict their migratory flights to the night. This makes their nocturnal departure timing a key factor determining the potential duration of migratory flights, which in turn affects their travel speed. Previous correlative studies revealed that part of the variation in nocturnal departure timing of migratory songbirds is explained by the respective length of the night, with birds departing earlier when nights are short. As the length of the night is inextricably linked to the time within the season, it has been impossible to ascertain which of the two factors drives variation in nocturnal departure timing. To virtually decouple both factors, that is, length of the night and time within the season, we conducted a series of short-term experiments using migratory songbirds caught at stopover. These birds were exposed to nights of either natural or shortened length. We found that birds exposed to shortened nights showed slightly earlier nocturnal departures than those exposed to the natural length of the night. This coincided with a seasonal pattern in the start of nocturnal migratory behaviour (migratory restlessness during the experimental period and actual departures following release) among birds, irrespective of the experimental treatment. Based on these results we suggest that birds' nocturnal departure timing pursues an innate seasonal schedule of migratory activity, which is adjusted to the current length of the night. Such a mechanistic framework provides the potential for cross-calibrating birds' innate seasonal schedule of migratory activity with the current spatiotemporal progress during migration.
       
  • Flexible use of simple and combined calls in female Campbell's monkeys
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Camille Coye, Karim Ouattara, Malgorzata E. Arlet, Alban Lemasson, Klaus ZuberbühlerCall combinations allow animals to expand the communicative power of small repertoires with acoustically inflexible elements. In Campbell's monkeys, Cercopithecus campbelli, males possess a small repertoire of calls that can be merged to an acoustically invariable suffix and which are concatenated into various sequences, mainly in response to external disturbances. The vocal repertoire of adult females has been less well studied although it is much richer, containing both alarm and various social calls. In particular, females possess a low-pitched contact call, produced either alone or merged with a high-pitched, arched unit. Combined contact calls are identity-richer and easier to detect than simple calls. Here, we investigated the socioecological factors that determined the production of single and combined utterances and found that combined utterances were more common when identity was relevant such as in mixed-species associations and during socially important vocal exchanges. In contrast, single calls were used mainly when predation risk was high, as part of this species' generally cryptic antipredator strategy. We discuss these finding in the light of current theories regarding the evolution of combinatorial signalling.
       
  • Ant nurse workers exhibit behavioural and transcriptomic signatures of
           specialization on larval stage
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Justin T. Walsh, Michael R. Warner, Adrian Kase, Benjamin J. Cushing, Timothy A. LinksvayerDivision of labour within and between the worker and queen castes is thought to underlie the tremendous success of social insects. Colonies might benefit if subsets of nurse workers specialize further in caring for larvae of a certain stage or caste, given that larval nutritional requirements depend on stage and caste. We used short-term (
       
  • Scatter-hoarding rodents are better pilferers than larder-hoarders
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Zhenyu Wang, Bo Wang, Xianfeng Yi, Chuan Yan, Lin Cao, Zhibin ZhangFood hoarding is critical to rodents for their survival and reproduction. However, the seeds cached by rodents often suffer heavy pilferage by competitors. Therefore, compensation for cache loss is crucial, especially for scatter-hoarding rodents, as they cannot aggressively defend their stored seeds, whereas larder-hoarding rodents can. Pilfering caches of other individuals may be an effective way to compensate for cache loss for rodents. Hence, cache pilfering is likely to be as important as hoarding to food-hoarding rodents. Scatter-hoarding rodents may rely on their olfactory abilities and explore a wide area to retrieve their cached seeds, which may help to increase the probability of encountering and pilfering others' caches, whereas it is not essential for larder-hoarding rodents. We hypothesized that rodents that showed stronger scatter-hoarding behaviour would be better pilferers. To test this hypothesis, we investigated the relationship between scatter-hoarding and pilferage behaviours among four coexisting species of rodents using seminatural enclosure experiments in southwest China. Both hoarding and cache pilfering differed significantly between the four species. The predominant scatter-hoarding rodents, red spiny rats, Maxomys surifer, had a strong cache-pilfering behaviour, whereas yellow-bellied rats, Rattus flavipectus, mainly adopted larder-hoarding strategies and had a weak cache-pilfering behaviour. Chinese white-bellied rats, Niviventer confucianus, and chestnut rats, Niviventer fulvescens, had moderate scatter-hoarding and cache-pilfering behaviours. The intensity of cache pilfering was negatively correlated with the intensity of larder hoarding, but positively correlated with the intensity of scatter hoarding among the coexisting food-hoarding rodents. Our study suggests that the positive correlation between the intensities of scatter hoarding and cache pilfering is likely to facilitate reciprocal pilferage among scatter-hoarding rodents, which helps to maintain the stability of scatter-hoarding behaviour in these populations.
       
  • In wolves, play behaviour reflects the partners' affiliative and dominance
           relationship
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Simona Cafazzo, Sarah Marshall-Pescini, Jennifer L. Essler, Zsófia Virányi, Kurt Kotrschal, Friederike RangePuppy packs (consisting of only puppies) and mixed-age packs (composed of puppies and adults) were observed to test whether social play can be used for assessing and establishing social relations in wolves, Canis lupus. Differently from previous studies, we looked at play behaviours in detail, allowing us to categorize play interactions as either competitive or relaxed, and predicted that different types of play would be associated with different relationships between individuals. We found that the more time dyads spent in relaxed play, the more affiliative interactions they exchanged outside of play. In the mixed-age packs, dyads that spent more time in both relaxed and competitive play showed fewer exchanges of aggressive behaviours. Conversely, in puppy packs, the more time dyads spent in competitive play, the more aggressive interactions were exchanged outside of play. Since clear dominance relationships emerged in the mixed-age packs, but not in puppy packs, we suggest that play can help to reduce the frequency of aggressive interactions only when a clear hierarchy exists between pack members. Furthermore, we found that in both puppy and mixed-age packs, dominance relationships were reflected and rarely reversed during play. Finally, dyads with a less clear dominance relationship spent more time playing in a competitive way. Overall, our results support the social assessment hypothesis suggesting that social relationships outside of play are reflected during playful interactions. Moreover, we revealed how different types of play, that is, playing in a competitive or relaxed way, may be related to different social relationships. This distinction between play types has not been acknowledged before but could help researchers better understand the functions of play in different species.
       
  • Relationships between personality and lateralization of sensory inputs
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Kyriacos Kareklas, Gareth Arnott, Robert W. Elwood, Richard A. HollandIn humans and other vertebrates, sensory information is sometimes lateralized towards one brain hemisphere that dominates the control of a task. Although sensory lateralization may depend on the stimuli being processed, the degree or direction of lateralization can differ according to behavioural phenotype. Accordingly, personality may play an important role in lateralization, yet there is a lack of evidence regarding how lateralizations are utilized to process information and promote a personality-based response to a particular situation. Here we show that simultaneous stimulus processing and organization of personality-based responses can be accomplished via differences in laterality between senses. We demonstrate this by examining novel object inspection in the weakly electric fish Gnathonemus petersii. We found that electrosensing is lateralized in this species, but differently between personality phenotypes: bold fish were lateralized towards the right hemisphere and timid fish the left. By contrast, visual laterality did not vary with personality; rather the left hemisphere was dominant across the population, as is common for fish when visually analysing unfamiliar objects. This evidence reveals differences in functional laterality between sensory systems and the role of personality in eliciting these differences. The species has a stronger input of electrical signals than visual signals in its brain; therefore, sensory representation in the brain might drive the laterality differences.
       
  • Olfactory eavesdropping of predator alarm pheromone by sympatric but not
           allopatric prey
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Shihao Dong, Ping Wen, Qi Zhang, Yuan Wang, Yanan Cheng, Ken Tan, James C. NiehEavesdropping is predicted to evolve between sympatric, but not allopatric, predator and prey. The evolutionary arms race between Asian honey bees and their hornet predators has led to a remarkable defence, heat balling, which suffocates hornets with heat and carbon dioxide. We show that the sympatric Asian species, Apis cerana (Ac), formed heat balls in response to Ac and hornet (Vespa velutina) alarm pheromones, demonstrating eavesdropping. The allopatric species, Apis mellifera (Am), only weakly responded to a live hornet and Am alarm pheromone, but not to hornet alarm pheromone. We observed typical hornet alarm pheromone-releasing behaviour, hornet sting extension, when guard bees initially attacked. Once heat balls were formed, guards released honey bee sting alarm pheromones: isopentyl acetate, octyl acetate, (E)-2-decen-1-yl acetate and benzyl acetate. Only Ac heat balled in response to realistic bee alarm pheromone component levels (
       
  • Stereotypic behaviours are heterogeneous in their triggers and treatments
           in the American mink, Neovison vison, a model carnivore
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Andrea Polanco, María Díez-León, Georgia MasonStereotypic behaviours (SBs) are common in confined animals including captive Carnivora, which display diverse forms of SB: often whole-body movements (e.g. pacing), but also head-only movements (e.g. head twirling) and ‘scrabbling’ (scratching at enclosure boundaries). Although often pooled together, emerging evidence indicates that SBs are heterogeneous, suggesting that subtypes differ in their causes, triggers, and consequently treatments. In mink, a model carnivore, scrabbling seems to be elicited by neighbouring conspecifics. We tested this hypothesis via three studies of 32 males (individually caged in rows and separated by solid partitions). Study 1 investigated whether neighbour proximity affects the location of any SBs, and Study 2, whether removing neighbours reduces any SBs. Results revealed that although mink typically avoided proximity to their neighbours, scrabbling was uniquely directed towards neighbours who were close to the shared cage partition. It was also the only SB significantly elevated by having all-male neighbours, and reduced by removing neighbours. Study 3 then investigated whether environmental enrichment, a standard SB treatment, would reduce or abolish different SBs equally, to assess whether scrabbling is simply easier to alleviate than other SBs. Enrichment reduced all SB subtypes, but logistic regressions revealed that the odds of complete abolition were higher for whole-body and head-only SBs than for scrabbling. Overall, these naturally solitary carnivores thus seem to avoid conspecific proximity, but they specifically direct their stereotypic scrabbling at neighbours; and their scrabbling is reduced by neighbour removal, while their whole-body and head-only SBs are instead better alleviated with enrichment. Understanding that carnivore SBs are heterogeneous in their triggers and most effective treatments may help zoos, breeding centres and mink farms improve the design of their enclosures and the efficacy of their enrichments.
       
  • Presence of an audience and consistent interindividual differences affect
           archerfish shooting behaviour
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Nick A.R. Jones, Mike Webster, Christopher N. Templeton, Stefan Schuster, Luke RendellThe social environment can play an important role in shaping the foraging behaviour of animals. In this study we investigated whether archerfish, Toxotes jaculatrix, display any behavioural changes in response to the presence of an audience while using their specialized foraging tactic of shooting, spitting precisely aimed jets of water, at prey targets. As any prey items shot down are potentially available to competitors, we hypothesized that shooting fish would be sensitive to the presence of potential competitors, especially given the suggestion that, in the wild, this species shows intraspecific kleptoparasitism and faces interspecific competition. We found that in the presence of another fish, archerfish took longer to shoot, made more orientations (aiming events) per shot, and tended to be closer to the target at the time of shooting. Additionally, archerfish showed high interindividual differences in latency to shoot, and these differences were consistent across contexts, with and without an audience. Our results show that archerfish are sensitive to, and adjust their shooting behaviour in response to, the presence of an audience and highlight the importance of social context in this fish species. We also suggest that interindividual differences may play an important role in archerfish shooting behaviour. This study highlights the importance of social effects and competition on foraging behaviour and decision making. Further work in this species could explore whether differences in competitive foraging ability are linked to sensitivity to the presence of an audience.
       
  • Evidence for vocal performance constraints in a female nonhuman primate
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Dena J. Clink, Russell A. Charif, Margaret C. Crofoot, Andrew J. MarshallTrilled vocalizations, wherein notes are repeated in rapid succession, are found in a variety of taxa including oscine birds, singing mice and nonhuman primates. Previous work on birds and singing mice has provided evidence of vocal performance constraints in trills, where there is a trade-off between the rate of the note repetition and the bandwidth (or frequency range) of each note. Here, we investigate vocal performance constraints in the trilled portion of the female contribution to the duet in the Bornean gibbon, Hylobates muelleri, recorded from seven sites in Sabah, Malaysia. We used two approaches. First, to ensure that our results were comparable with previous studies on vocal performance constraints, we used a 90% quantile regression to examine the relationship between trill rate and bandwidth. We found that there was a significant negative correlation between bandwidth and trill rate. Second, we formally compared multiple hierarchical models to identify the best predictors of bandwidth and trill rate. Our top model predicting bandwidth showed that trill rate and location within the trill were reliable predictors of bandwidth. With trill rate as the response variable, our top model included location within the trill as well as trill duration. We found that there were no important site-level differences in bandwidth but that trill rate varied predictably among sites. Our analyses provide strong evidence for performance constraints in the production of trills in Bornean gibbon females. Further research is needed to determine whether higher-performance trills provide honest signals of caller quality and whether gibbons respond differently to low- and high-performance calls.
       
  • Habitat complexity and predictability effects on finding and collecting
           food when ants search as cooperative groups
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Kaleda K. Denton, Peter NonacsCooperatively foraging groups have two sequential goals: to find food and thereafter efficiently exploit or retrieve it. Previous research has largely focused on searching behaviours of individuals or organization of food retrieval processes, rather than on how groups initially distribute themselves to find ephemeral food items that are unpredictable in time and space. In the present study, we examined how Argentine ants, Linepithema humile, search environments in anticipation of food appearing briefly in areas with differing spatial complexity. Nests were connected to three foraging arenas containing 1, 9 or 25 cells. Food appeared briefly in one cell each day, either randomly or more predictably in distant cells (but equally often in each arena). We recorded the number of ants in cells when food had not been recently present, and thereafter whether ants successfully located the food when presented. Surprisingly, as food location became more predictable, ants found it less frequently. Foragers were located more often in cells closer to the nest (i.e. at information ‘choke points’ that returning foragers needed to traverse), and in cells with higher connectivity and greater centralness within foraging arenas. Such distributions reduce search coverage area but likely increase information transmission. Thus, it appears that L. humile foragers distribute themselves to favour rapid recruitment when food is found rather than maximizing food encounter rates. Although the reduced foraging success with more predictably located food suggests that ants did not adjust expectations in a Bayesian manner within arenas towards individual cells, they did appear Bayesian across arenas. Because foragers missed food more often in higher-complexity arenas than in lower-complexity arenas, this could increase perceptions that the latter are more rewarding. Shifts in distributions were consistent with such biased perceptions. Future studies to determine whether other group-foraging species use analogous solutions would be highly useful.
       
  • Presence and lasting effect of social referencing in dog puppies
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Claudia Fugazza, Alexandra Moesta, Ákos Pogány, Ádám MiklósiSocial referencing is the process by which individuals utilize cues from emotional displays of a social partner to form their response to a new situation. Social referencing can provide advantages, especially to young, inexperienced individuals, by favouring an appropriate reaction to novel situations while avoiding the risks of trial and error learning. While there is evidence for social referencing from humans in adult dogs, Canis familiaris, the ontogeny of this behaviour has not been investigated. Moreover, it is not known whether dogs acquire some information during such interactions and recall it later, when encountering a similar situation. We tested 8-week-old companion dog puppies (N = 48) of various breeds by exposing them to a novel stimulus in the presence of human or conspecific social partners. With humans, we tested the effect of different emotional signals expressed by the informant. With conspecifics, we tested whether the presence of the subject's mother or an unfamiliar dog affected behaviour towards the stimulus. Puppies alternated their gaze between the stimulus and the social partner (referential looking) with all the partners. Puppies tested in the presence of a human expressing positive emotional signals towards the stimulus were more likely to approach it than puppies tested with a human expressing neutral emotional signals (behavioural regulation). Importantly, this effect was still apparent after a delay of 1 h, when puppies were tested alone. Puppies tested in the presence of their mother were more likely to approach the stimulus than puppies tested alone or with an unfamiliar dog. The results of this study show that the ability for social referencing develops early in the ontogeny of companion dogs as it is already present at 8 weeks. The valence of the emotional cues provided by a human social partner and the presence of the mother affect the behaviour of puppies exposed to novel situations, even after a delay.
       
  • Differential effects of brain size on memory performance in parasitic
           wasps
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Emma van der Woude, Martinus E. Huigens, Hans M. SmidSmall animals usually have relatively larger brains than large animals. This allometric brain–body size scaling is described by Haller's rule. However, one of the smallest known insects, Trichogramma evanescens, a parasitic wasp, shows brain isometry, leading to similar relative brain sizes in small and large conspecifics. The somewhat larger Nasonia vitripennis parasitic wasp displays diphasic brain–body size scaling with isometry in small individuals and allometry in large individuals. These two species may have undersized brains for small wasps, with reduced cognitive abilities. Here, we induced intraspecific body size variation in genetically identical T. evanescens and N. vitripennis and examined cognitive trade-offs of brain scaling. We compared visual and olfactory memory retention between small and large conspecifics. Results showed that diphasic brain scaling affected memory retention levels in N. vitripennis, whereas isometric brain scaling did not affect memory retention in T. evanescens. The two species may experience different evolutionary pressures that have shaped the cognitive consequences of isometric brain–body size scaling. A possible trade-off of brain isometry in T. evanescens could be present in brain properties other than memory performance. In contrast, it may be more adaptive for N. vitripennis to invest in other aspects of brain performance, at the cost of memory retention.
       
  • Brood provisioning and reproductive benefits in relation to habitat
           quality: a food supplementation experiment
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Martin U. Grüebler, Martina Müller, Vanja T. Michel, Marco Perrig, Herbert Keil, Beat Naef-Daenzer, Fränzi Korner-NievergeltFood availability is a major characteristic of habitat quality, linking habitats with demographic parameters such as reproductive performance. Parent birds adjust their food provisioning to both habitat-specific food characteristics and the demands of their young. However, because habitat quality and the brood's food intake are often correlated, the underlying mechanisms of adjustments in parental provisioning remain entangled. How the relationship between habitat quality and parental provisioning behaviour affects the quantity of food available to nestlings and the resulting nestling growth and survival is therefore still incompletely established. We experimentally increased the food intake of little owl, Athene noctua, nestlings in two habitat types differing in food availability and used unsupplemented broods as controls. The food supplementation experiment allowed us to disentangle the effect of habitat type from the effect of the nestlings' food intake on parental provisioning behaviour. Camera traps recording a series of 10 consecutive images for each parental visit allowed us to quantify visiting rates and diet composition by applying a hierarchical multinomial model explicitly accounting for the observation process. Food supplementation caused parents to switch to smaller food items and to increase visiting rates, resulting in similar biomass brought to nestlings in supplemented and unsupplemented broods. Irrespective of the food supplementation, parents in low-quality habitats delivered 63% of the biomass delivered by those in high-quality habitats. Accordingly, we found an increase in nestling survival rates in response to food supplementation in low-quality habitats, but not in high-quality habitats. Our results show that habitat quality affects the biomass of prey delivered to the brood, whereas the nutritional state of the brood affects prey selection or foraging modes of parents. Reproductive output directly reflected habitat quality in terms of food availability, identifying food as the main factor underlying differential reproduction within and between populations.
       
  • Estimating the robustness and uncertainty of animal social networks using
           different observational methods
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Grace H. Davis, Margaret C. Crofoot, Damien R. FarineSocial network analysis is quickly becoming an established framework to study the structure of animal social systems. To explore the social network of a population, observers must capture data on the interactions or associations between individuals. Sampling decisions significantly impact the outcome of data collection, notably the amount of data available from which to construct social networks. However, little is known about how different sampling methods, and more generally the extent of sampling effort, impact the robustness of social network analyses. Here, we generate proximity networks from data obtained via nearly continuous GPS tracking of members of a wild baboon troop (Papio anubis). These data allow us to produce networks based on complete observations of interindividual distances between group members. We then mimic several widely used focal animal sampling and group scanning methods by subsampling the complete data set to simulate observational data comparable to that produced by human observers. We explore how sampling effort, sampling methods, network definitions and levels and types of sampling error affect the correlation between the estimated and complete networks. Our results suggest that for some scenarios, even low levels of sampling effort (5–10 samples/individual) can provide the same information as high sampling effort (>64 samples/individual). However, we find that insufficient data collected across all potentially interacting individuals, certain network definitions (how edge weights and distance thresholds are calculated) and misidentifications of individuals in the network can generate spurious network structure with little or no correlation to the underlying or ‘real’ social structure. Our results suggest that data collection methods should be designed to maximize the number of potential interactions (edges) recorded for each observation. We discuss the relative trade-offs between maximizing the amount of data collected across as many individuals as possible and the potential for erroneous observations.
       
  • African elephants use plant odours to make foraging decisions across
           multiple spatial scales
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Melissa H. Schmitt, Adam Shuttleworth, David Ward, Adrian M. ShraderMammalian herbivores are known to be extremely selective when foraging, but little is known about the mechanisms governing the selection of patches and, at a finer scale, individual plants. Visual examination and direct sampling of the vegetation have previously been suggested, but olfactory cues have seldom been considered. We examined the use of olfactory cues by foraging African elephants, Loxodonta africana, and asked whether they use plant odours to select specific patches or plants when making feeding decisions. Scent-based choice experiments between various preferred and nonpreferred plants were conducted across two spatial scales (between plants and between patches). We used coupled gas chromatography–mass spectrometry (GC–MS) analysis of headspace extracts of volatile organic compounds emitted by the different plant species to explore similarities among the overall odour profiles of each species. We found that elephants selected their preferred plant species across both spatial scales, probably using differences in plant odour profiles. The ability to differentiate between plant odours allowed elephants to reduce their search time by targeting preferred plant species both within a feeding station and between patches. This suggests that olfactory cues probably play an important role in driving herbivore foraging decisions across multiple spatial scales.
       
  • Mate copying in Drosophila melanogaster males
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Sabine Nöbel, Mélanie Allain, Guillaume Isabel, Etienne DanchinTo assess potential mates' quality individuals can observe sexually interacting conspecifics. Such social information use is called mate copying and occurs when observer individuals witnessing sexual interactions of conspecifics later show a mating preference for mates that were seen mating. Most studies have focused on female mate copying, as females are usually the choosy sex. However, much less is known about the existence of male mate copying, probably because of the usual strong asymmetry in sex roles. Mate copying has been documented in female Drosophila melanogaster, and here we report on experimental evidence for mate copying in males of this species in which females can actively reject males and prevent copulation. As mate choice implies high costs for males we assumed that they perform mate copying as well. We created two artificial female phenotypes by randomly dusting females with green or pink powders, and virgin naïve observer males were given the opportunity to see a demonstrator male choosing between a pink and a green demonstrator female. Immediately afterwards, observer males were given the choice between two new females, one of each colour. To circumvent the difficulty of determining actual male mate preference, we used two complementary indices of male mate choice, both of which provided evidence for male mate copying. Informed observer males showed a bias towards females of the colour they saw being chosen during demonstrations, while uninformed males chose randomly between pink and green females. This suggests that male fruit flies can also perform mate copying. Although significant, our results in males were less clear-cut than in females in previous studies. However, like females, D. melanogaster males can mate copy based on a single observation. The importance and generality of such mate copying abilities in nature, and their potential impact on the evolution of Drosophila and probably other invertebrates, need further exploration.
       
  • Age-dependent and social status-dependent behavioural plasticity of the
           cricket Gryllus bimaculatus
    • Abstract: Publication date: July 2018Source: Animal Behaviour, Volume 141Author(s): Toshiki Abe, Naoyuki Fujiyama, Hiroshi Tomimatsu, Toshiki NagayamaResponse patterns and underlying neural mechanisms of adaptive behaviours may be similar in different taxa. Among closely related species, this similarity may depend on shared innate motor programs. To test this hypothesis, we analysed the responses of the two-spotted cricket Gryllus bimaculatus to mechanical stimulation of the terminal abdominal appendages (cerci). Final instar juveniles (the last stage of insect larvae) mainly showed escape-like ‘dart’ responses to stimulation, while a defensive response (‘up’, ‘kick’ and ‘turn’ responses) increased in adult crickets. In older adults, the ‘turn’ response, in which animals turned towards the stimulus source and jerked their upper body in a threatening raised posture, became more frequent. Thus, the response patterns of crickets to tactile stimulation of the cerci changed from an escape response to a defensive response depending on age and growth. This behavioural plasticity was also dependent on social status. Paired crickets began fighting within 30 s to establish dominance status. Winning juveniles were more likely to show defensive responses and losing adults changed their response from defence to escape. This age- and social status-dependent behavioural plasticity is also observed in crayfish, suggesting a preservation of instinctive behavioural strategies in some arthropods.
       
  • Components of change and the evolution of learning in theory and
           experiment
    • Abstract: Publication date: Available online 28 June 2018Source: Animal BehaviourAuthor(s): Aimee S. Dunlap, Matthew W. Austin, Andreia FigueiredoTheoretical treatments of the evolution of learning have a long and rich history, and although many aspects remain unresolved, the consensus is that the predictability and timescale of environmental change play a crucial role in when learning evolves. Directly testing these ideas has proven difficult because comparative experiments must assume many often unknowable aspects of an evolutionary past. Even within the present, identifying and accurately quantifying the relevant types of change can be problematic. Controlling or manipulating change can be difficult in many taxa. Within the theory, what is meant by change can markedly vary between models. Here, we present a targeted comparison of models to show this variation, and argue that standardizing measures of change can add tractability to models. We first review how change is emphasized in models of learning evolution and then describe the still small literature that directly tests the evolution of learning via digital evolution and experimental evolution. We then give an example of how to tie specific natural history to larger theory on learning evolution using the flag model of reliability and certainty and foraging in bumblebees. Learning, by its nature, is of fundamental importance to many fields. Theoretical treatments of learning evolution have been growing at a rapid pace, often with limited empirical applicability to natural systems and little congruence on what is meant by change across models. By explicitly defining change and tying models to natural systems, we can greatly increase our ability to not only understand when learning should evolve, but also when learning does evolve.
       
  • Culture and cultural evolution in birds: a review of the evidence
    • Abstract: Publication date: Available online 9 June 2018Source: Animal BehaviourAuthor(s): Lucy M. AplinSocial learning from the observation of knowledgeable individuals can allow behaviours, skills and techniques to spread across populations and transmit between generations, potentially leading to emergent cultures. An increasing body of research has not only evidenced the occurrence of cultural behaviour in nonhuman animals, but also hypothesized that such cultures could ‘evolve’ over time in a way that shares key characteristics with biological evolution, including through a process of selection on variance, inheritance and adaptation. Outside of humans, song and contact calls in birds provide by far the most comprehensive evidence for culture and cultural evolution. However, birds have often been considered ‘one-trick cultural ponies’, only exhibiting significant diversity in this single component of their behavioural repertoire. Recent studies have begun to challenge this view. Here, I review the evidence across multiple behavioural domains for wild cultures in birds. I then discuss the evidence in birds for four key concepts of cultural evolution: (1) variation, selection, inheritance, (2) adaptation, (3) geographical and demographic processes and (4) the accumulation of modifications. I incorporate the evidence from birdsong with other behavioural domains for each key concept and identify important gaps in knowledge. Finally, I discuss how taking a cultural evolution perspective can be informative for our understanding of cognitive ecology more broadly.
       
  • Animal expertise: mechanisms, ecology and evolution
    • Abstract: Publication date: Available online 5 June 2018Source: Animal BehaviourAuthor(s): Reuven DukasExpertise consists of the features that allow individuals with extensive experience on a given complex task to show superior performance on that task compared to novices. While expertise has been investigated mostly in humans, it is highly relevant for other species as well because it can have strong effects on fitness. Moreover, studying expertise in nonhumans can help us understand human expertise. Several features that distinguish experts within their domain of expertise from novices include (1) greater long-term memory, (2) larger capacity of working memory, (3) better ability to focus attention on the most relevant concurrent tasks, (4) superior ability to anticipate, perceive and comprehend the relevant elements in one's surroundings, (5) quicker and better decisions, and (6) faster and more coordinated motor movements. The development of expertise follows a characteristic pattern of gradual improvement in performance over extended periods devoted to practising a given complex task. Heritable variation in a few traits can affect the rate of expertise acquisition and its peak levels. These traits include motivation to practise, perseverance, basic cognitive abilities such as attention span, working memory capacity, learning rates and memory retention, and various physiological, anatomical and morphological features. Key environmental factors influencing expertise development are parental and social settings, which may encourage investment in the extended practice necessary for achieving superior performance on complex tasks. Future work on the evolutionary biology of expertise should focus on the yet unknown neurobiological mechanisms that underlie it, heritable variation in the traits that enable expertise and their genetic basis, further quantifications of expertise acquisition in natural settings, the fitness consequences of the traits that facilitate top expert performance, and the ecological and evolutionary consequences of expertise.
       
  • The cognition of ‘nuisance’ species
    • Abstract: Publication date: Available online 30 May 2018Source: Animal BehaviourAuthor(s): Lisa P. Barrett, Lauren A. Stanton, Sarah Benson-AmramRecent work in animal cognition has focused on how animals respond to new or changing environments. Although many species are currently in decline, other species are thriving in human-altered habitats by taking advantage of new resources and opportunities associated with anthropogenic disturbance. Yet, as a result, these same species are often in conflict with humans and treated as a nuisance. Therefore, cognitive abilities such as innovation and behavioural flexibility may, paradoxically, lead to the demise of especially adaptive individuals. Here we review what is known about the cognition of ‘nuisance’ species and ‘problem’ individuals to shed light on the struggles of coexistence with humans along disturbed landscapes. We take an in-depth look at several cognitive abilities that are hypothesized to be of critical importance for species that are successfully utilizing human-altered environments, including neophilia, boldness, categorization, innovation, memory, learning, social learning and behavioural flexibility, and examine evidence that these cognitive abilities may also bring animals into conflict with humans. We also highlight some examples of species that may be using cognitive mechanisms to change their behaviour to avoid conflict with humans. We then discuss the role of animal cognition in current mitigation strategies that have been developed to address human–wildlife conflict. Additionally, we consider the role that human behaviour and perception of animals might play in either worsening or lessening conflict with wildlife. Finally, we propose some directions for future research and suggest that empirical investigation of ‘nuisance’ animal cognition could reveal the cognitive mechanisms underlying adaptation to anthropogenic change as well as help mitigate human–wildlife conflict.
       
  • ‘Crazy love’: nonlinearity and irrationality in mate choice
    • Abstract: Publication date: Available online 18 May 2018Source: Animal BehaviourAuthor(s): Michael J. Ryan, Rachel A. Page, Kimberly L. Hunter, Ryan C. TaylorChoosing a mate is one of the most important decisions an animal can make. The fitness consequences of mate choice have been analysed extensively, and its mechanistic bases have provided insights into how animals make such decisions. Less attention has been given to higher-level cognitive processes. The assumption that animals choose mates predictably and rationally is an important assumption in both ultimate and proximate analyses of mate choice. It is becoming clear, however, that irrational decisions and unpredictable nonlinearities often characterize mate choice. Here we review studies in which cognitive analyses seem to play an important role in the following contexts: auditory grouping; Weber's law; competitive decoys; multimodal communication; and, perceptual rescue. The sum of these studies suggest that mate choice decisions are more complex than they might seem and suggest some caution in making assumptions about evolutionary processes and simplistic mechanisms of mate choice.
       
  • Spatial memory and cognitive flexibility trade-offs: to be or not to be
           flexible, that is the question
    • Abstract: Publication date: Available online 21 March 2018Source: Animal BehaviourAuthor(s): Maria C. Tello-Ramos, Carrie L. Branch, Dovid Y. Kozlovsky, Angela M. Pitera, Vladimir V. PravosudovCognitive flexibility allows animals to readily acquire new information even when learning contingencies may rapidly change, as is the case in highly variable, but predictable, environments. While cognitive flexibility is broadly thought to be beneficial, animals exhibit inter- and intraspecific variation, with higher levels of flexibility associated with reduced memory retention and vice versa. In this review, we discuss when and why such variation may exist and focus specifically on memory and memory flexibility. We argue that retained memories may negatively affect the acquisition of new information, most likely via proactive interference, and available data suggest that there may be a trade-off between memory retention and acquiring new memories. We discuss neurogenesis-mediated forgetting as the mechanism reducing memory interference, as new neurons enhance learning new information but also cause forgetting of older memories. Selection may be expected to favour either end of the continuum between memory retention and memory flexibility depending on life history and environment. More stable environments may favour memory retention over flexibility whereas rapidly changing environments may favour flexibility over retention. Higher memory capacity also seems to be associated with higher memory interference, so higher neurogenesis rates associated with forgetting of unnecessary information may be favoured when higher capacity is beneficial such as in food-caching species. More research is necessary to understand whether inter- and intraspecific differences in the association between memory retention and flexibility are related to some general ecological patterns, whether this association is heritable, and whether developmental conditions and experience have different effects on this association in different species.
       
  • Breeding clusters in birds: ecological selective contexts, mating systems
           and the role of extrapair fertilizations
    • Abstract: Publication date: Available online 2 March 2018Source: Animal BehaviourAuthor(s): Regina H. Macedo, Jeffrey Podos, Jeff A. Graves, Lilian T. ManicaSociality beyond mated pairs, whether in the form of nesting colonies, clustered territories or leks, presents an evolutionary puzzle because densely packed individuals typically incur high fitness costs. One hypothesis to explain clustered distributions is that they overlie clumped distributions of resources. However, numerous studies have shown that resource distributions are often insufficient to explain individuals' settlement decisions, suggesting that clustered breeding distributions are driven by other types of benefits, possibly related to ecological, social and genetic factors. One can ask more specifically whether animals cluster because of some underlying ecological factor, or whether aspects of their reproductive behaviour and mating systems are more influential. Accordingly, evaluating the influence of sexual selection upon the evolution of mating systems can be crucial for understanding the underlying causes of animal aggregations. In this article, we review the behavioural ecology of three types of mating systems where breeding occurs in clusters: colonial, lekking and socially monogamous clustered territorial systems. We highlight sexual selection as a potential explanation for the emergence of aggregations in all three cases. In particular, we discuss the hidden lek hypothesis, which postulates that aggregations in colonial and territorial species can be driven by increased opportunities for extrapair copulations. Finally, we feature our work with the blue-black grassquit, Volatinia jacarina, which illustrates the complexity of selective mechanisms that may favour territorial aggregations.
       
  • The spatial dynamics of female choice in an exploded lek generate benefits
           of aggregation for experienced males
    • Abstract: Publication date: Available online 7 February 2018Source: Animal BehaviourAuthor(s): Emily H. DuVal, Carla C. Vanderbilt, Leithen K. M'GonigleThe spatial distribution of prospective mates can dramatically affect the process and outcome of mate choice. In a variety of species, spacing between males influences the likelihood that females visit particular individuals or respond to competing signals. Discrimination by females is expected to be highest among neighbouring males, yet males of some species aggregate in ways that apparently facilitate such comparisons. To better understand the selective pressures affecting male aggregation, we investigated how spatial organization of male territories related to female mate sampling tactics and male mating success in the lance-tailed manakin, Chiroxiphia lanceolata. This species displays in a dispersed lek of alpha males, each of which usually has a subordinate beta partner that participates in displays but does not mate with females attracted by their cooperative courtship. We video-recorded courtship activity at display perches of 12 alpha–beta pairs for 42 days in 2013, and documented 478 visits by 82 banded females. We further quantified the relationship of aggregation with genetic mating success for 49 alphas displaying at georeferenced locations in 5 years. Males with close neighbouring alphas were visited by more females, but geographic centrality was unrelated to female visit frequency. Females moved shorter distances between consecutive courtship visits than expected at random, but only 20.5% of 73 females visiting males with video-monitored nearest neighbours visited both neighbouring alpha males. Effects of aggregation on annual genetic reproductive success were only evident after accounting for the stronger effects of alpha age and experience, and only experienced alphas benefited from having close neighbours. Selection for aggregation more likely influences social behaviour of older alphas than settlement decisions by younger males. Benefits of aggregation for experienced alphas mitigate declines in old age, and may generate selective pressure favouring the long-term social alliances that are a key characteristic of this mating system.
       
  • Social costs are an underappreciated force for honest signalling in animal
           aggregations
    • Abstract: Publication date: Available online 6 January 2018Source: Animal BehaviourAuthor(s): Michael S. Webster, Russell A. Ligon, Gavin M. LeightonAnimals in social aggregations use signals of quality or motivation to attract mates and intimidate rivals. Theory indicates that honesty can be maintained in these signals if the costs of signalling affect low-quality individuals more than they affect high-quality individuals. Considerable research has focused on identifying the nature of those costs and their ability to maintain honest signals. Much of this research, particularly in recent years, has focused on receiver-independent physiological costs of signal production. Less research attention has been paid to receiver-dependent costs that might arise from conspecific responses to signals. Here we survey the literature on these different types of costs, focusing in particular on case studies from a diversity of taxa. We find that signals often do carry significant physiological production costs, but this is not universal, as many signals appear to be physiologically inexpensive to produce. More importantly, very few studies have tested the key prediction that physiological production costs differentially affect low-quality individuals over high-quality individuals. In contrast, research from a diversity of taxa indicates that signals such as coloration and vocalizations often affect agonistic interactions, which in turn affect the production of signals, and that deceptive signallers receive more aggression than do honest signallers in at least some systems. Social costs are a plausible but understudied mechanism for maintaining honest signalling.
       
 
 
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